No-back mechanisms have long been used in a variety of applications wherein a load is moved bidirectionally by a motor or prime mover or the like and wherein in at least one direction of movement, some force existing on the load can operate to cause the load to drive the prime mover or motor. Examples include winch systems and actuating systems for control surfaces on aircraft.
In the design of conventional no-back mechanisms, brakes are employed and are typically called into play when a load tends to drive the prime mover or motor. In a typical brake so used, the coefficient friction may vary as much as 300% depending upon humidity, oil in the environment and other factors. As a consequence, many such no-back mechanisms are designed for the worst case situation, namely, to act effectively for the least coefficient of friction that may be encountered.
This in turn results in a typical no-back mechanism being over designed for normal usage. This over design adds to the cost of the no-back mechanism as well as to the weight thereof. Excessive cost is always undesirable as is excessive weight, particularly in one frequent environment of use of no-back mechanisms, aircraft.
The present invention is directed to overcoming one or more of the above problems.